Fixing Floorboards to a concrete slab

Thanks for the advice i still have not made up my mind which way to go but i will let you all know how it turns out

Bosco

I haven't had any experience with this, and prolly never will (love a real polished timber floor though) but just thought I'd relate something I saw. It was a year ago while visiting my family in Perth, in a very upmarket display home. The floor was Aussie hardwood I think, laid directly on a slab I reckon 'cos of the height, lack of steps and the concrete hard feel, but the whole thing looked appalling. The sun was shining through a huge french door (opening onto a landscaped pool of course) throwing shadows...and each board was cupped so much it looked like it was corrugated:eek: . I surmised that the top was drying at a faster rate (shrinking) than the underside, as it is was sealed-in against the concrete, therefore expanding upwards at the long joins. Certainly put me off ever contemplating such a floor. My opinion is that any method of fixing the boards so air is free to circulate (ie. a floating floor) would balance the drying rate, and solve the cupping problem.

Anyone with experience feel free to comment about this, perhaps I just saw a poor job, or a one-in-a-million situation.
Cheers,

Andy
air is not free to circulate under a floating floor. If a proper membrane is used on a dry concrete slab all should be well with the direct stick, but personally I prefer a traditional timber floor (besides, I'm a carpenter and prefer laying bearers and joists on stumps to pouring a concrete slab :rolleyes: )

Mick

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Originally Posted by Andy Mac

. I surmised that the top was drying at a faster rate (shrinking) than the underside, as it is was sealed-in against the concrete, therefore expanding upwards at the long joins. Cheers,

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The theory is partially correct. Its not the air drying it (rather the opposite depending on the weather) but the moisture coming out of the slab that is the problem.

The area not to skimp on is the moisture barrier and timber, or rather the quality control of the timber. You can have what ever type of timber you like but it wont matter wether its the best in the world if the miller/timber yard has not dried it properly. Then you have to ask how has the timber been handled and stored since it left the yard. I regularly see shiploads of Kapur arriving in Fremantle, stored on open decks unprotected???...This timber often goes to certain large hardware chain stores for sale to the unsuspecting public.

A rule of thumb for the concrete slab is it must be a least six months old before applying a timber floor.

If you have confidence in the quality control of your supplier, then follow the advice of the other posts as you see fit.

Cheers

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Originally Posted by slats

Hi bosco. I am a professional floor installer i deal in bamboo flooring but have installed a lot of varieties by direct stick method. Dont let the cowboys put you off direct stick. Firstly put down a moisture barrier which is applied by a roller and is very simple to do. Just like painting a floor. If your slab is a under 5%
moisture they say there is no need for a moisture barrier.Do it any way and all future problems are solved.Then stick it down with sika bond glue applied with a notched trowled.Floors that i have done are some ten years old with no problems.Done probaly direcy stick is the best and cheapest way.
Regards Gary.

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Hi Gary,
I am about to lay ironbark tongue and groove boards to a concrete slab and am wondering the best way to go. Direct to slab (Old home) or laying battens will may affect the height too much.

If i can avoid battens i'd like to.
What is the name of the glue i'd need and what procedure would you suggest?

I've been told i should lay builders plastic, masonite then glue boards? would this work?

Any help would be appreciated.
Thanx